The present invention relates to a developing apparatus which develops an electrostatic latent image formed on an image bearing member by using a developing agent. More particularly, the invention relates to a developing apparatus which comprises a developing agent carrier with an elastic member being urged against a surface, thereof. A developing agent layer is then formed on the surface of the developing agent carrier through the elastic member upon the movement of the developing agent carrier, and the developing agent layer is, opposed to the image carrier. The latent image is thereby developed.
In conventional developing apparatuses which use a one-component developing agent, in order to form a developing agent layer on a developing agent carrier, an elastic blade formed of urethane rubber or stainless steel is pressed against a surface of the developing agent carrier. For example, when a nonmagnetic developing agent is used, the developing agent is charged by friction between the elastic blade and the developing agent carrier. Therefore, in order to form a good visible image, the developing agent must be uniformly charged at a desired potential and the contact width between the elastic blade and the developing agent carrier must be widely set.
However, in the conventional developing apparatuses, it is very difficult to set the contact width between the elastic blade and the developing agent carrier at a desired value. For example, if a central portion of the elastic blade, excluding its edge portions, is brought into firm surface contact with the developing agent carrier, the contact width thereof can be increased to some extent. However, in this case, the contact pressure between the elastic blade and the developing agent carrier becomes excessive. Particularly, when a cylindrical developing agent carrier is used and the diameter thereof is decreased, it becomes still more difficult to set the contact width between the elastic blade and the developing agent carrier to a large width.